Past literature has well documented the effect of board networks on corporate investments, governance and managerial compensation. Using a network of 9,393 directors in 985 public US-based firms, I find that cost of debt increases in board interconnectedness. High information flow through directorship interlocks increases debt holders’ monitoring costs on firms with more central boards. In particular, shocks in R&D investments and capital expenditures, M&A activity, change of operating segments and analysts’ forecast error are positively related to board centrality. In line with the monitoring costs hypothesis, higher information flow further decreases accounting quality and impedes efficient private information exchange in lending transactions. Overall, the results suggest that networks’ information asymmetry is a critical component in debt pricing.